JP2964666B2 - Catalytic combustion device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalytic combustion apparatus for heating, heating, drying, etc. by catalytically burning a gaseous or liquid fuel, and more particularly to a catalytic combustion apparatus having excellent exhaust gas purification characteristics.

[0002]

2. Description of the Related Art Conventionally, a catalytic combustion apparatus for heating, heating, drying and the like by catalytically burning gaseous fuel or liquid fuel is shown in FIG.
The configuration shown in FIG.

[0003] The configuration will be described below with reference to FIG. As shown in the figure, fuel and air are supplied to a vaporization chamber 4 by a pump 2 and a fan 3 provided in a fuel tank 1, and the fuel is vaporized in the vaporization chamber 4 and mixed with air, and then the primary combustion section 5 and is ignited by an ignition device 6 to form a flame. The high-temperature combustion exhaust gas is discharged from the exhaust port 8 through the catalyst layer 7, during which the catalyst layer 7
Is heated and heated. When it is detected that the temperature of the catalyst layer 7 has reached a temperature sufficient to perform catalytic combustion (the detection section is not shown), the pump 2 is stopped, and the flame of the primary combustion section 5 is extinguished. Thereafter, when the pump 2 is operated again to supply the fuel, the flame is not formed in the primary combustion section 5 and flows into the catalyst layer 7 as a premixed gas. Here, the catalyst layer 7
Since the temperature has risen sufficiently, catalytic combustion is started and complete combustion is performed. Since the catalytic combustion proceeds exclusively on the upstream surface of the catalyst layer 7, that portion becomes a radiation radiator and is transmitted and radiated to the entire surface through the glass window 9.

[0004]

In such a conventional catalytic combustion device, fuel premixed with air undergoes an oxidation reaction in the catalyst layer 7 to generate carbon dioxide and water along with heat of reaction.

[0005] Here, if the temperature and heating time of the catalyst layer 7 are sufficient, a complete combustion reaction is carried out. However, a low-temperature portion such as the peripheral portion of the catalyst layer 7 or an excessively rich mixture or a pre-lean mixture of the pre-mixed gas. There has been a problem that a portion in contact with the air-fuel mixture cannot be completely burned, and some HC and intermediate products, particularly CO, of the fuel are generated.

[0006] Furthermore, the activity of the catalyst cannot be avoided from thermal degradation, and the activity of the catalyst decreases with the passage of time.
There was a problem that the generation of C and CO increased.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a catalytic combustion device capable of preventing incomplete combustion and maintaining normal exhaust gas purification characteristics for a long period of time.

[0008]

In order to achieve the above object, the present invention provides a main catalyst layer for combustion and an auxiliary catalyst layer disposed downstream of the main catalyst layer for purifying exhaust gas. And a secondary air supply unit is provided between the main catalyst layer and the auxiliary catalyst layer. Further, an air supply amount control means for controlling the supply amount of the secondary air in accordance with the oxygen concentration in the combustion gas discharged from the main catalyst layer is provided.

The fuel cell system further includes a main catalyst layer for performing combustion, and an auxiliary catalyst layer disposed downstream of the main catalyst layer for purifying exhaust gas, wherein a main catalyst layer is disposed between the main catalyst layer and the auxiliary catalyst layer. A cooling unit for the combustion gas is provided, and cooling amount control means for controlling a cooling amount of the cooling unit in accordance with the oxygen concentration of the combustion gas discharged from the main catalyst layer is provided. Further, a cooling amount control means for controlling a cooling amount of the cooling unit according to a temperature of the auxiliary catalyst layer and a temperature of the combustion gas discharged from the main catalyst layer and an oxygen concentration of the combustion gas is provided. is there.

[0010]

According to the present invention, a secondary air supply unit is provided between the main catalyst for combustion and the auxiliary catalyst for purifying exhaust gas, and the secondary air is supplied to the secondary air supply unit. By mixing with the combustion gas, the oxygen concentration in the combustion gas increases, so that the activity of the auxiliary catalyst layer can be increased. Thereby, purification of HC and CO in the auxiliary catalyst layer can be performed very favorably. Further, by monitoring the oxygen concentration of the combustion gas discharged from the main catalyst layer and controlling the amount of secondary air mixed with the combustion gas by the air supply amount control means, the oxygen concentration of the combustion gas sent to the auxiliary catalyst layer is controlled. Can be controlled, and the auxiliary catalyst layer can function optimally.

In addition, a cooling portion for the combustion gas is provided between the main catalyst layer and the auxiliary catalyst layer, and the temperature of the combustion gas and the temperature of the auxiliary catalyst layer are controlled according to the oxygen concentration of the combustion gas discharged from the main catalyst layer. By controlling by means, the temperature of the auxiliary catalyst layer can be controlled, and the auxiliary catalyst layer can function optimally.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a first embodiment of the present invention. As shown in FIG. 1, reference numeral 10 denotes a fuel tank, and 11 denotes a fuel supply pump for supplying fuel to a vaporization chamber (hereinafter, referred to as a premixing chamber) 13. , 12 are blowers for supplying air to the premixing chamber 13. The premixing chamber 13 is provided with a heater (not shown) for heating. A primary combustion section 14 is provided downstream of the premixing chamber 13, and an ignition device 15 is provided near the primary combustion section 14.
A secondary combustion section 18 having a main catalyst layer 16 and an auxiliary catalyst layer 17 is provided downstream of the primary combustion section 14, that is, downstream of the premixing chamber 13. The secondary combustion section 18 is formed by the main catalyst layer 16 and the auxiliary catalyst layer 17 provided on the downstream side thereof, and communicates with the exhaust port 19. And the main catalyst layer 1
Between the auxiliary catalyst layer 6 and the auxiliary catalyst layer 17, a secondary air supply unit 20 supplied from the blower fan 12 via a secondary air supply pipe 21
Is formed.

In the above configuration, the fuel and the air are supplied to the premixing chamber 13 by the fuel supply pump 11 and the blower fan 12, and the fuel is vaporized in the premixing chamber 13 and mixed with the air. 14 and is ignited by an ignition device 15 to form a flame. The high temperature combustion exhaust gas heats and raises the temperature of the main catalyst layer 16, and when it is detected that the temperature of the main catalyst layer 16 has reached a temperature sufficient to perform catalytic combustion (a detection unit is not shown), the fuel supply pump 11 Is stopped,
The flame of the primary combustion section 14 is extinguished. Thereafter, when the fuel supply pump 11 is operated again to supply fuel to the premixing chamber 13, a flame is not formed in the primary combustion section 14 and flows into the main catalyst layer 16 as a premixed gas, Main catalyst layer 1
At 6 the catalytic combustion is started.

At this time, in a low temperature portion such as a peripheral portion of the main catalyst layer 16 or a portion in contact with a rich mixture or a lean mixture of the premix, the premix cannot be completely burned, and the HC and CO are not completely combusted. Occurs.

On the other hand, in the present embodiment, the main catalyst layer 16
Since the auxiliary catalyst layer 17 is provided on the downstream side, HC and CO contained in the combustion gas in the main catalyst layer 16 can be completely reacted and purified by the auxiliary catalyst layer 17 and discharged from the outlet 19. .

Further, in the catalytic combustor, the catalytic reaction proceeds at a very high temperature, so that it is difficult to avoid thermal degradation of the catalyst.

On the other hand, in this embodiment, the combustion part of the catalyst is divided into two parts. That is, it is divided into a high-temperature main catalyst layer 16 that performs most of the combustion and a low-temperature auxiliary catalyst layer 17 that combusts HC and CO that cannot be completely burned by the main catalyst layer 16. However, in order to prevent incomplete combustion and maintain normal exhaust gas purification characteristics for a long period of time, it is necessary to increase the activity of the auxiliary catalyst layer 17 and make it function optimally.

FIG. 2 shows the purification rate of the catalyst with respect to the catalyst temperature using the oxygen concentration in the test gas as a parameter. As is clear from FIG. 2, as the catalyst temperature increases, the purification rate also increases, and the activity of the catalyst increases. Furthermore, at the same catalyst temperature, the higher the oxygen concentration in the test gas, the higher the purification rate, and the higher the activity of the catalyst.

The present invention is based on such a phenomenon. In FIG. 1, a part of the combustion air from the blower fan 12 is supplied from the secondary air port 22 through the secondary air supply pipe 21 to the main catalyst layer. The air is supplied to a secondary air supply unit 20 formed between the auxiliary catalyst layer 16 and the auxiliary catalyst layer 17. Then, the secondary air is mixed with the combustion gas to increase the oxygen concentration in the combustion gas, and flows into the auxiliary catalyst layer 17.

[0021]

In the first embodiment of the present invention, FIG.
As shown, the flow control valve 2 is provided in the middle of the secondary air supply pipe 21.
4, an oxygen sensor 23 is provided in the secondary air supply unit,
It is preferable to form air supply control means by these.
No. With this configuration, the combustion supplied to the auxiliary catalyst layer 17
The oxygen concentration of the gas can be constantly monitored,
Oxygen necessary for obtaining a predetermined purification rate in the medium layer 17
Activate the flow control valve 24 to adjust the concentration,
The secondary air for combustion is supplied from the fan 12 to the secondary air supply unit 20.
From the auxiliary catalyst layer 1 by mixing with the combustion gas.
Control the oxygen concentration of the combustion gas supplied to 7 to an optimum value
be able to.

As a result, the activity of the auxiliary catalyst layer 17 is reduced.
And the purification of CO and HC in the auxiliary catalyst layer 17 becomes higher.
It was performed very well and the main catalyst layer 16 did not burn enough
CO and HC can be completely purified.

Next, FIG. 4 shows a second embodiment of the present invention. As shown in FIG. 4, a combustion gas cooling section 25 is provided between the main catalyst layer 16 and the auxiliary catalyst layer 17. I have. A cooling amount control means is formed by the oxygen sensor 23 and the cooling fan 26, and the cooling fan 26 attached to the container wall and sending air to the cooling unit 25 is operated by a signal from the oxygen sensor 23 provided in the cooling unit 25. Then, the cooling amount of the cooling unit 25 is controlled.

Here, the cooling air sent to the cooling section 25 cools the auxiliary catalyst layer 17 and cools the auxiliary catalyst layer 17 so as to maintain the auxiliary catalyst layer 17 at a temperature below an allowable temperature at which it functions stably. The amount is set, and when the oxygen sensor 23 detects a low oxygen concentration, the cooling amount is controlled so as to raise the temperature of the auxiliary catalyst layer 17 within the allowable temperature.

In the above configuration, when the oxygen concentration in the combustion gas discharged from the main catalyst layer 16 decreases, the activity of the auxiliary catalyst layer 17 decreases unless the temperature of the auxiliary catalyst layer 17 is maintained at a high temperature (see FIG. 2). At 23, the oxygen concentration in the combustion gas is detected, and when the oxygen concentration is low, the cooling fan 26 is controlled to reduce its cooling amount and increase the temperature of the auxiliary catalyst layer 17.

As a result, the activity of the auxiliary catalyst layer 17 is increased to function optimally, and HC and CO are efficiently purified.

FIG. 5 shows a third embodiment of the present invention. As shown in FIG.
The cooling fan 26 is operated by a signal from a temperature sensor 27 for detecting the temperature of the auxiliary catalyst layer 17 and an oxygen sensor 23 for detecting the oxygen concentration of the combustion gas. The amount is controlled.

FIG. 6 shows a fourth embodiment of the present invention. As shown in FIG.
The cooling fan 26 includes a temperature sensor 28 for detecting the temperature of the combustion gas discharged from the main catalyst 16 and an oxygen sensor 2 for detecting the oxygen concentration of the combustion gas.
It operates according to a signal from the control unit 3 to control the cooling amount of the cooling unit 25.

In the configuration of the third and fourth embodiments, the signals from the temperature sensors 27 and 28 and the signal from the oxygen sensor 23 are sent to the cooling fan 26, and the temperature of the combustion gas and the temperature of the auxiliary catalyst layer 17 are increased. The amount of cooling by the cooling fan 24 is controlled so that the temperature becomes an optimum temperature according to the oxygen concentration in the combustion gas. This makes it possible to control the combustion temperature of the auxiliary catalyst layer 17 with high accuracy, appropriately deal with fluctuations in the combustion load in the main catalyst layer 16, and make the auxiliary catalyst layer 17 function optimally. .

The temperature sensor 27 may be directly attached to the auxiliary catalyst layer 17 as in this embodiment, or may be provided close to the auxiliary catalyst layer 17.

The temperature sensors 27 and 28 may detect the temperature of the combustion gas and the temperature of the auxiliary catalyst layer 17 by detecting the temperature and light using a thermocouple, an optical sensor, or the like. It is.

Further, in the above-described embodiment, the catalytic combustion apparatus using petroleum as a fuel has been described. However, a similar result is obtained with a fuel using gas as a fuel, and the type of fuel is not limited. Further, there is no significant difference depending on the material and shape of the catalyst body, and similar results are obtained by using a braided ceramic fiber body or a metal honeycomb body.

As described above, according to the embodiment of the present invention, the secondary air supply section or the cooling section 25 is formed between the main catalyst layer 16 and the auxiliary catalyst layer 17, and the secondary air supply section or the cooling section 25 is formed depending on the oxygen concentration or the temperature. By controlling the amount of secondary air or the temperature of the auxiliary catalyst layer 17,
There is an effect that the catalytic activity of the auxiliary catalyst layer 17 can function optimally.

[0035]

As is apparent from the above description of the embodiment, according to the present invention, the main catalyst layer and the auxiliary catalyst layer are provided in the combustion section, and the secondary air is interposed between the main catalyst layer and the auxiliary catalyst layer. By providing a supply unit and controlling the supply amount of the secondary air in accordance with the oxygen concentration in the combustion gas discharged from the main catalyst layer, the catalytic activity of the auxiliary catalyst layer can be optimally functioned. It is possible to provide a catalytic combustor that can prevent combustion and maintain normal exhaust gas purification characteristics for a long period of time.

Further, a main catalyst layer and an auxiliary catalyst layer are provided in the combustion section, and a cooling section for the combustion gas is provided between the main catalyst layer and the auxiliary catalyst layer, and the cooling is performed according to the oxygen concentration of the combustion gas discharged from the main catalyst layer. Optimum catalytic activity of the auxiliary catalyst layer by controlling the cooling amount of the auxiliary catalyst layer and controlling the cooling amount of the cooling section according to the temperature of the auxiliary catalyst layer and the temperature of the combustion gas discharged from the main catalyst layer It is possible to provide a medium combustor that can function and can prevent incomplete combustion and maintain normal exhaust gas purification characteristics for a long period of time.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a configuration of a catalytic combustion device shown in a first embodiment of the present invention.

FIG. 2 is a catalyst purification characteristic diagram for explaining the catalytic activity of an auxiliary catalyst layer.

FIG. 3 is a side sectional view showing the configuration of the catalytic combustion device according to the first embodiment of the present invention .

FIG. 4 is a side sectional view showing the configuration of the catalytic combustion device of the second embodiment.

FIG. 5 is a side sectional view showing the configuration of the catalytic combustion device of the third embodiment.

FIG. 6 is a side sectional view showing the configuration of the catalytic combustion device of the fourth embodiment.

FIG. 7 is a side sectional view showing a configuration of a conventional catalytic combustion device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 13 Premixing chamber 16 Main catalyst layer 17 Auxiliary catalyst layer 20 Secondary air supply part 23 Oxygen sensor 25 Cooling part 26 Cooling fan 27 Temperature sensor 28 Temperature sensor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F23C 11/00 306 F23C 6/04 303 F23C 6/04 305

Claims (4)

(57) [Claims] 1. A premixing chamber for mixing fuel and primary air, a main catalyst layer having a plurality of communication holes disposed downstream of the premixing chamber, and a main catalyst layer disposed downstream of the main catalyst layer. and an auxiliary catalyst layer having a set have been a number of communication holes, and the secondary air supply unit between the auxiliary catalyst layer and the main catalyst layer, the main catalyst layer
Air according to the oxygen concentration in the combustion gas discharged from the
A catalytic combustion device provided with air supply amount control means for controlling the supply amount of air . 2. A pre-mixing chamber for fuel and air, a main catalyst layer having a plurality of communication holes disposed downstream of the pre-mixing chamber,
An auxiliary catalyst layer having a large number of communication holes disposed downstream of the main catalyst layer, wherein a cooling unit for combustion gas is provided between the main catalyst layer and the auxiliary catalyst layer, and the main catalyst layer A catalytic combustion device provided with cooling amount control means for controlling the cooling amount of the cooling unit in accordance with the oxygen concentration of the combustion gas discharged from the combustion unit. 3. A pre-mixing chamber for fuel and air, and a main catalyst layer having a large number of communication holes disposed downstream of the pre-mixing chamber.
An auxiliary catalyst layer having a large number of communication holes disposed downstream of the main catalyst layer, and a cooling unit for combustion gas provided between the main catalyst layer and the auxiliary catalyst layer; A catalytic combustion device comprising cooling amount control means for controlling a cooling amount of the cooling unit according to a temperature of a bed and an oxygen concentration of a combustion gas discharged from the main catalyst layer. 4. A premixing chamber for fuel and air, a main catalyst layer having a plurality of communication holes disposed downstream of the premixing chamber,
An auxiliary catalyst layer having a large number of communication holes disposed downstream of the main catalyst layer, wherein a cooling unit for combustion gas is provided between the main catalyst layer and the auxiliary catalyst layer; A catalytic combustion device comprising cooling amount control means for controlling a cooling amount of the cooling unit according to a temperature and an oxygen concentration of a combustion gas discharged from a bed.